Fusion of $\mathrm{MnO}_{2}$ with KOH in presence of $\mathrm{O}_{2}$ produces a salt $\mathbf{W}$. Alkaline solution of $\mathbf{W}$ upon eletrolytic oxidation yields another salt $\mathbf{X}$. The manganese containing ions present in $\mathbf{W}$ and $\mathbf{X}$, respectively, are $\mathbf{Y}$ and $\mathbf{Z}$. Correct statement(s) is (are)

(B) Both $\mathbf{Y}$ and $\mathbf{Z}$ are coloured and have tetrahedral shape; (C) In both $\mathbf{Y}$ and $\mathbf{Z}$, $\pi$-bonding occurs between p -orbitals of oxygen and d-orbitals of manganese.; (D) In aqueous acidic solution, $\mathbf{Y}$ undergoes disproportionation reaction to give $\mathbf{Z}$ and $\mathrm{MnO}_{2}$.

(A) $\mathbf{Y}$ is diamagnetic in nature while $\mathbf{Z}$ is paramagnetic

d and f Block Elements — JEE Advanced · 2019 · 27 May 2019 · Paper 1 Question with Solution

Fusion of

MnO_{2}

with KOH in presence of

O_{2}

produces a salt

W

. Alkaline solution of

W

upon eletrolytic oxidation yields another salt

X

. The manganese containing ions present in

W

and

X

, respectively, are

Y

and

Z

. Correct statement(s) is (are)

(A) $Y$ is diamagnetic in nature while $Z$ is paramagnetic
(B)Both $Y$ and $Z$ are coloured and have tetrahedral shape✓ Correct
(C)In both $Y$ and $Z$ , $π$ -bonding occurs between p -orbitals of oxygen and d-orbitals of manganese.✓ Correct
(D)In aqueous acidic solution, $Y$ undergoes disproportionation reaction to give $Z$ and $MnO_{2}$ .✓ Correct

Answer: (B), (C), (D)

Solution

MnO_{2} + 2 KOH + \frac{1}{2} O_{2} Δ K_{2} MnO_{4} + H_{2} O

W =

K_{2} MnO_{4}

, ion Y =

MnO_{4}^{2 -}

(manganate, Mn in +6 state, one unpaired electron, paramagnetic).

Electrolytic oxidation:

MnO_{4}^{2 -} \to MnO_{4}^{-} + e^{-}

X =

KMnO_{4}

, ion Z =

MnO_{4}^{-}

(permanganate, Mn in +7 state, no unpaired electrons, diamagnetic).

(A) FALSE: Y is paramagnetic, Z is diamagnetic.
(B) TRUE: Both ions are tetrahedral and colored.
(C) TRUE: Both have pπ-dπ bonding between O and Mn.
(D) TRUE: In acidic solution,

3 MnO_{4}^{2 -} + 4 H^{+} \to 2 MnO_{4}^{-} + MnO_{2} + 2 H_{2} O

JEE Advanced · 2019 · 27 May 2019 · Paper 1 · One or more correct options

LIST-I	LIST-II
(I) $[Cr (CN)_{6}]^{4 -}$	(P) $t_{2 g}$ orbitals contain 4 electrons

LIST-I

LIST-II

(I)

[Cr (CN)_{6}]^{4 -}

(P)

t_{2 g}

orbitals contain 4 electrons

JEE Advanced · 2019 · 27 May 2019 · Paper 1 · d and f Block Elements

Solution

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